重复频率强流电子束的产生和传输实验研究

 电子束真空二极管重复频率运行时，它将表现出与单次运行时不同的特点。在电子束产生过程中，屏蔽半径应尽可能地小，且击穿延时时间较短，故选择石墨作为阴极材料。实验结果表明：在重复频率运行时，当环型阴极环厚较薄时，阴极的发射电流密度较大，因此对阴极的加热效应也加强，等离子体的膨胀速度加快，从而使得二极管阻抗减小，最后几次输出的电子束的电流较大，而电压减小；当重复频率较高时，由于加热效应使得阴极等离子体膨胀速度加快，最后几个脉冲阴极发射能力增强，波形重复性变差；当引导磁场强度增大时，阴极等离子体受到较大的磁场力约束，横向膨胀速度减慢，从而使得电子发射面积减小，总发射电流减小，二极管的阻抗增大。最后取引导磁场为1.5 T，阴极环厚为1 mm，得到重复频率100 Hz、束压827 kV、束流8.22 kA、脉冲波形之间重复性很好的均匀电子束输出。

Experimental study on the generation and transmission of the high-current repetitive electron beam

When vacuum electron diode is repetitively operated, it presents some peculiar characteristics. Because of its small screening radius and short delay time, graphite is chosen as the cathode material. In experiments, the following results were attained: (1) when the annular cathode is thinned or the repetitive rate is increased, because of thermal effect of current and quickening expanding speed of plasma, the consistency of pulses in a burst is worsened; (2) with the strength of guiding magnetic field increased, the plasma is more restricted and expand slower, and the total current, as well as the electron-emitting area is reduced and the impendence of diode is increased. At last, when the strength of guiding magnetic field is 1.5 T and the cathode is 1 mm thick, a uniform electron beam of 827 kV, 8.22 kA, 100 Hz is obtained.